One fact, to begin with, thrusts itself upon our attention, a fact of deep interest and so exceptional that this is the first example with which my entomological studies have presented me. In each burrow laid bare I always find two collaborators, a pair: I find the male lending the mother his assistance. The household duties are divided between the two. My notes give the following scene, to which we can easily restore its animation according to the pose of the immobilized actors. The male is at the back of the gallery, squatting on a length of sausage measuring barely an inch. He occupies the basin formed through the stuff’s being packed more tightly in the centre of each stratum. What was he doing before the violation of his home? His attitude tells us clearly: with his sturdy legs, especially the hind-legs, he was pressing down the last layer placed in position. His mate occupies the upper floor, almost at the opening of the burrow. I see her holding between her legs a great lump of material which she has just gathered at the bottom of the heap surmounting the house. The scare caused by my intrusion has not made her let go. Hanging up there, above space, braced against the walls of the pit, she clasps her burden with a sort of cataleptic obstinacy. The nature of the interrupted work is easily guessed: Baucis was carrying down to Philemon, the stronger of the two, the wherewithal to continue the arduous work of piling and trampling. After laying the egg and surrounding it with those delicate precautions of which a mother alone possesses the secret, she had handed over the construction of the cylinder to her companion, confining herself to playing the humble part of a caterer’s man. Similar scenes, observed during different phases of the work, enable me to draw a general picture. The sausage begins with a short, wide casing which closely lines the bottom of the burrow. In this bag, with its yawning mouth, I find the two sexes in the midst of materials crumbled and possibly weeded before being pressed, so that the grub may have first-class victuals within its reach as soon as it starts feeding. The couple between them plaster the walls and increase their thickness until the cavity is reduced to the size needed for the hatching-chamber. This is the moment for laying the egg. Withdrawing discreetly, the male waits with materials ready to close the cell that has just been filled. The closing is done by bringing the edges of the sack nearer together and adding a ceiling, a hermetically cemented lid. This is the delicate part of the work, calling for knack much more than strength. The mother alone attends to it. Philemon is now a mere journeyman-mason: he passes the mortar, without being allowed on the ceiling, which his brutal pressure might cause to fall in.